I like Marco rock because it allows you to take your time building rock structures by cementing pieces together into the shapes you want. I’ve started two tanks with it. On the first one, I moved fast, adding fish and corals as soon as the tank was cycled. Some green hair algae came in on a frag and absolutely took over the tank for 18 months until I finally got it under control. Now, three years in, the rock looks aged and has coralline growing on it. But the hair algae battle was not fun. I think it took over because there was nothing to compete with it for space on the rocks.
I started my second tank last year with Marco rock and also a couple pounds of live rock rubble from KP Aquatics. This time I went way slower. I made my rock structures and then cycled them in a plastic bin for a couple months. When the nitrogen cycle was finished, I dosed phosphate until I got consistent readings telling me the rocks had absorbed enough phosphate to match the water. At that point I added the rocks to the new tank and added the live rock rubble, which came in with coralline algae, sponges, tiny oyster/clams, and a couple baby pencil urchins. I waited another six weeks before adding a clean-up crew from Indo Pacific Sea farms. A week after that I added fish and a few coral frags.
Anyway, that’s probably more than you wanted to know, and probably sounds like an excruciatingly slow process. I would have been too impatient for that approach with my first tank. But I will say that with this second tank I’ve had no ugly stage at all other than a brief cyano outbreak that never really got too bad. I wouldn’t say my corals have exploded with growth yet, but overall things seem to be maturing nicely, and if you looked at the tank now, 10 months in, you wouldn’t be able to tell the live rock from the Marco rock — there are sponges, coralline, and little mollusks growing everywhere.
TL/DR - Dry rock seeded with live rock and taking each stage sloooow can work great.
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